Vehicle altitude control system

ABSTRACT

An altitude control system for guiding a submarine vehicle in such manner as to search for and hunt along a reference altitude above the sea floor having a sonar range signal generator, a vehicle pitch signal generator, an adjustable reference altitude voltage source, and a series-connected summing amplifier and direct current level detector coupled to the aforesaid range and pitch signal generators and said reference altitude voltage source for automatically regulating the control surfaces of said submarine vehicle in accordance with the algebraic sum of the output signals therefrom.

Sttes atent Foley [451 I Feb. 29, 1972 [54] VEHICLE ALTITUDE CONTROL3,123,797 3/1964 Ehrrnan ....340/l SYSTEM 3,153,220 10/ i964 Hagemann..340/3 [72] Inventor: James W. B. Foley, Lanesboro, Mass. PrimaryExaminer-Richard A. Farley 731 Assignee: The United States at America asand represented by the Secretary of the Navy [57] ABSTRACT [22] Filed:1966 An altitude control system for guiding a submarine vehicle in 2APPL 599,993 such manner as to search for and hunt along a referencealtitude above the sea floor having a sonar range signal generator, avehicle pitch signal generator, an adjustable reference U.S. Cl. ..340/3R, 1 T, altitude voltage ource and a seriemnngcted am- 3 3/ T plifierand direct current level detector coupled to the [51] Int. Cl ..G0ls9/66 aforesaid range and pitch signal generators and said reference [58]Field of Search ..340/3, 3 T, 16 R, l; 343/7 TA; altitude voltage sourcefor automatically regulating the con- 1 14/25 ftrol surfaces of saidsubmarine vehicle in accordance with the algebraic sum of the outputsignals therefrom. 56 R f l 1 v e 9 Claims, 4 Drawing Figures UNITEDSTATES PATENTS 1mm w M 2,962,997 l 2 l 99 $te d an ..l l4/25 VEHICLEMAXIMUM 36 A N'IE c 43 A- Ee GEN. REGULATOR 31 29 32 33 34 3a 39 4| 4TIME g i I i BLANK VOLTAGE VEHICLE iii? mmsszizt 5mm?" 025$ 23:32;

6 i I 6 2| 35 ALTITUDE 37 42 READOUT VbLTAGE VEHICLE REPE ION 27OSCICLATOR DETECTOR RECEIVER 24 22 23 TRANSDUCER TRANSMITTER rmmsmrrznOSCILLATOR JQ Y E PAIENTEUFEB29 1912 l SHEET 1 BF 2 PATENTEDFEBZS m23,646,507 sum 2 0F 2 I so M|LL|sEcoNos-I-3o MlLLlSECONDS-I (o) N I\ I(b) W40 KC/SEC. PULM M l l\ (g) I 1 I i v F/6.3. (1) 7 I (k) (I) M (n) II I I INVENTOR. JAMES W. B. FOLEY Aim/40 I ATTO EY VEHICLE ALTITUDECONTROL SYSTEM The present invention relates generally to closed-loopfeedback control systems and, in particular, is a vehicle altitudecontrol system. In even greater particularity, it is a system forautomatically controlling the altitude and pitch of aselfpropelled,moving submarine vehicle in such manner as to cause it to seek and huntalong a preset altitude above the floor of the ocean.

In the past, devices have been devised that perform substantiallysimilar control functions; but, for the most part, they were usuallysomewhat inaccurate, were complex and expensive to manufacture,burdensome to handle and operate, and, in general, left a great deal tobe desired from reliability, efficiency, and speed-of-operationstandpoints. Moreover, some of such devices utilized echo-ranging sonarin conjunction with vehicle-towing apparatus, and, accordingly, they didnot independently and automatically seek the desired altitude but,instead, only followed it once it was acquired.

The present invention overcomes most of the disadvantages of the knownprior art devices, in that it will enable a selfpropelled underwatervehicle to simply and automatically dive from the sea surface, detectthe sea floor during the dive, and level off at some preselectedaltitude above the bottom. In addition, it is ostensively a considerableimprovement over the prior art, in that, once acquired, it will followcomparatively low altitudes with accuracy.

It is, therefore, an object of the invention to provide an improvedclosed-loop, feedback, automatic control system.

Another object of this invention is to provide an improved vehiclealtitude control system.

Still another object of this invention is to provide an improved methodand means of making a moving submarine vehicle automatically dive belowthe sea surface, detect the sea floor during the dive, seek apreselected altitude above said sea floor, and accurately hunttherealong.

A further object of this invention is to provide an improved automaticaltitude control system for a self-propelled underwater vehicle.

Another object of this invention is to provide a vehicle altitudecontrol system that will closely follow relatively low controlaltitudes.

Another object of this invention is to provide a method and means forenabling a submarine vehicle to accurately follow a preselected altitudeabove the sea floor while traveling at relatively high speed.

Still another object of this invention is to provide a vehicle controlsystem that is easily and economically manufactured, operated, andmaintained. I

Other objects and many of the attendant advantages will be readilyappreciated as the subject invention becomes better understood byreference to the following detailed description when considered inconjunction with the accompanying drawings wherein:

FIG. 1 is a simplified block diagram of a functional systemincorporating the subject invention; and

FIG. 2 is a more detailed block diagram of the subject invention;

FIG. 3 is an idealized graphical representation of the output signalsfrom the various elements of the device of FIG. 2; and

FIG. 4 is a simplified quasi-pictorial view of a submarine vehicle whichmay incorporate the subject invention to an advantage.

Referring now to FIG. 1, there is shown a Fathometer 11 for measuringthe altitude and altitude change of a movable vehicle. Similarly, thealtitude or pitch and pitch change of said movable vehicle is measuredwith respect to a horizontal datum by a pendulum pitch signal generator12. Outputs of said fathometer and pitch signal generator are bothapplied to a pair of inputs of a summing amplifier 13. An altitudesetting signal or voltage is also applied to an input of summingamplifier 13, and this signal acts as the control altitude voltagebecause it is so summed in summing amplifier 13 that it cancels thevoltage present therein when the pitch is zero and the vehicle isrunning at the desired height above the bottom.

The output 'of summing amplifier 13 is connected to the input of a DCvoltage level detector 14, the output of which is effectively connectedto the vehicle elevators 15 which, in turn, varies the altitude anddirection of vehicle 16 in such manner as to make it seek and hunt alonga preselected altitude.

The embodiment of the invention depicted in greater detail in FIG. 2shows a repetition rate oscillator 21 which, in effect, produces a clockpulse that is used as the basic timing unit for the entire system.

The output of repetition rate oscillator 21 is coupled to the input of atransmitter oscillator 22 for the timely production of a CW ping-typesignal. A transmitter power amplifier 23 is connected between the outputof said transmitter oscillator 22 and the input of a transducer 24.

Since in this particular instance the vehicle to be controlled is anunderwater vehicle, the aforesaid transducer 2 8 is a reversibleelectroacoustical transducer which broadcasts acoustical energythroughout the subaqueous environmental medium in which it is operatingin response to an electrical signal supplied to the input thereof, andgenerates an electrical output signal in response to an acousticalsignal received from said subaqueous environmental medium within whichit is submerged. Although transducer 24 is defined as being anelectroacoustical transducer that is part of a sonar type system thatoperates in a submarine environment, it should be understood that in theevent the operational environment is something other than aqueous (sayatmospheric, for example), an appropriately designed transducer may besubstituted therefor. Obviously, so doing would be well within thepurview of the artisan having the benefit of the teachings herewithpresented.

Being reversible, the output signal of transducer 24 is connected to theinput of a receiver 27, which may, for instance, contain such signalprocessing elements as limiters, filters, amplifiers, etc., in order toput it into a more useful form. The output of receiver 27 is connectedto the input of a detector 28, the output of which is, in turn, coupledto one of the inputs of an AND-gate 29.

The aforementioned repetition rate oscillator 21 also has its outputconnected to the input of a variable blanking signal generator 31, andone of the outputs thereof is connected to the other input of AND-gate29. The output of AND-gate 29 and the other output of the aforesaidblanking signal generator 31 are respectively applied to a pair ofcompatible inputs of a time comparator multivibrator 32, which, toeffect this particular function, is preferably a properly designedbistable multivibrator that changes state according to the presence ofthe inputs thereto, with the blanking signal input overriding the inputfrom AND-gate 29 to effectively stop it from passing therethrough, aswill be explained in greater detail subsequently in the discussion ofthe operation of the entire invention.

The output of time comparator multivibrator 32 is coupled to the inputof an integrator 33, with the operative signal output thereof connectedto one of the inputs of a summing amplifier 34, and the indicator outputthereof optionally connected to the input of any appropriate indicatingand/or recording readout 35. Readout 35 may, for example, be a recorder,or the like, which records the direct current voltage of the outputsignal of integrator 33 wither directly or in terms of the measureddistance to the sea floor or other datum, if so desired. 7

A vehicle pitch analog generator 36, which generates an electricalsignal that is proportional to the pitch angle of the vehicle from thehorizontal, has its output connected to another of the inputs of summingamplifier 34. Generator 36 may, for instance, be a suitably poweredpotentiometer, with a pendulum effectively connected to the movable armthereof in such manner that, when it moves due to a change in vehiclepitch, a potential proportional to said movement is supplied to summingamplifier 34.

A zero setting device 37 is connected to still another input of summingamplifier 34 in such manner as to supply a direct .rurrent voltagethereto which represents the control altitude point. It is preferablymanually or otherwise adjustable, in order that the control altitude.which the vehicle automatically follows, may be changed as necessary tomeet operational requirements and circumstances.

The output of summing amplifier 34 is coupled to the input of a voltagelevel detector 38, which determines whether or not a prescribedthreshold voltage has been reached. The output thereof is coupled to anormally deenergized relay 39 in such manner that when said prescribedthreshold voltage has been reached it becomes energized.

iRelay 39 is so connected to a vehicle control surface 41, such as, forexample, an elevator, that, in its deenergized contlition, isautomatically urged toward and, thus, calls for a down elevatorposition. while In its energized condition, it calls for an up elevatorposition. Of course, as is conventional with underwater vehicles. a downelevator position causes a vehicle 42 to dive toward the seafloor and anup elevator position causes it to climb toward the sea surface.

The foregoing up and down elevator signals are restricted to certainlimits which prevent the vehicle from diving at too great an angle.Accordingly, a maximum dive angle regulator 3 may be any preferred type,but it has been found that a simple mercury switch securely mounted as alevel on the vehicle and in parallel with the longitudinal axis thereofserves this purpose very well.

At this time, it would perhaps be well to mention that all of theelements disclosed in block form in the devices of FIGS. I and 2 arewell known and conventional per se; therefore, it is to be understoodthat it is their concerted arrangement, new combination, and newinteractions that constitute the subject invention and produce the newand improved results effected thereby.

The operation of the invention Wlll now be discussed briefly inconjunction with all of the figures ofthe drawing as follows:

As may readily be seen by inspection of FIG. 1. the inputs to theinvention are signals representing vehicle altitude and vehicle pitch.They are. of course, supplied thereto as a result of the vehiclealtitude and pitch being measured by a Fathometer and pitch pendulum, orthe like, respectively. As the vehicle altitude and pitch are beingcontinuously measured, their representative signals are addedproportionally in the summing amplifier, along with a control altitudeanalog voltage or a zero set, as it is herewith defined. The summingamplifier output voltage is then used to move the elevator controlsurfaces in such manner that the vehicle they are controlling respondsthereto to cause the input altitude and pitch voltages to cancel thezero set control point voltage. At the time such cancellation occurs,the vehicle will be running at in bstantially the preselected altitudeand Wlll continue to hunt therealong, until acted upon by some outsideforce or adjusted to do otherwise.

How the aforementioned broadly defined operation is actually effected,will now be discussed in connection with the device of FIG. 2. inasmuchas it functionally discloses the actions and interactions performed bythe elements illustrated therein.

Referring now to FIG. 2. as previously suggested, repetition rateoscillator 21 is actually a clock pulse generator which generates aseries of timing pulses, similar to those shown in FIG. 3(a), at apreselected frequency. Said timing pulses are then used as the basictiming units for the remainder of the invention. The frequency of saidclock pulses is. of course, a matter of design choice, and accordingly,should be selected to as to make the invention operable in any givenmedium. llowever, since the preferred embodiment disclosed herewith tSintended to operate in an aqueous environment, the clock pulse frequencyis preferably selected to be such as to allow 30 milliseconds betweensuccessive ones thereof.

The timing pulse output of repetition rate oscillator 21 is applied toand timely triggers transmitter oscillator 22, which generates a fourhundred kilocycle per second ping-type CW signal of predetermined lengthcomparable to that shown in FIG. 3(b). This signal is then amplified toa more useful level by power amplifier 23 before being applied totransducer 24. In response to said amplifier 23 before being applied totransducer 24. In response to said amplified input signal, transducer 24broadcasts an acoustical sonar signal proportional thereto down towardthe sea floor, from which it is reflected back as an acoustical echosignal somewhat similar to that represented by FIG. 3(2), which is thentimely received by transducer 24. Being reversible, transducer 24converts the received acoustical echo into a proportional electricalsignal that is supplied to receiver 27 for appropriate filtering,limiting, amplifying, and other processing as warranted to optimize thecharacteristics thereof. This improved signal is then detected to obtainthe envelope thereof and also maintain the same polarity therein, afterwhich it is applied in substantially the form illustrated in FIG. 30) toone of the inputs of AND gate 29.

The timing pulse of repetition rate oscillator 21 is also supplied toblanking generator 31, which produces a blanking signal of the typeidealized in FIG. 3(d) that is applied to the other of the inputs ofAND-gate 29. As a result of said blanking signal, AND-gate 29 is closedto the detected echo signal for approximately twice the length of thetransmitted pulse. The closed or delay period thereof is set by theblank generator. in order to permit the high reverberation immediatelyfollowing the transmitted ping to die out before the echo thereof lSreceived. After this period, the gate is opened, which then permits thedetected echo signal to pass therethrough, to timely trigger timecomparator multivibrator 32 to an off condition. Of course, if it werenot for the blank generator, the subect system would confuse thetransmitted ping or the reverberation immediately following the pingwith an excessively large echo signal.

At the same time repetition rate oscillator 21 initially triggerstransmitter oscillator 22 for effecting broadcast of the ping, it alsosupplies a trigger pulse similar to that shown in FIG. 3(0) preferablybut not necessarily via blank generator 31 to time comparatormultivibrator 32 to turn it on, thereby initiating the signal thereatand therefrom which acts as the range measuring reference datum. Ofcourse, as previously mentioned, when time comparator multivibrator 32receives the aforementioned signal from ANDgate 29, after thereverberation immediately following the transmitted ping has beenblanked out, it is turned off. The period of time it is turned on is ameasure of the round trip distance to the ocean bottom; hence. theoutput signal therefrom reflects this time element in its waveform shownin FIG. 3(g), as well as being proportional to the distance thesubmarine vehicle is from the sea floor at any given instant.

The output signal of time comparator multivibrator 32 is integrated byintegrator 33 to produce a signal waveform similar to that shown in FIG.3(h), in order to combine the discrete on" portions thereof occurringonce each ping-echo cycle and. thus, provide a direct current analogvoltage (see FIG. J(i)) that is proportional to the distance to oraltitude above the sea floor at that particular instant.

This distance or altitude DC analog voltage is then algebraically addedin summing amplifier 34 to a pair of other control voltages suppliedthereto. One of such control voltages is supplied by altitude setvoltage generator 37 and is exemplarily shown in FIG. 30). It, ofcourse, is the set point voltage that is proportional to the altitudeabove the sea floor at which the controlled vehicle is intended to berun. When this set voltage [5 added to that of FIG. 3(i) only, such aswhen excessive vehicle pitch is not occurring, its waveform would appearas it is shown in FIG. 3(k), and this waveform, therefore, representsthe deviation of the submarine vehicle from its set point altitude atany given instant. However, inasmuch as in actual operation some vehiclepitch is occurring practically all of the time, a voltage comparable tothat shown in FIG. 3(1), representing said pitch, is supplied by vehiclepitch analog generator 36 and added to the two voltages of FIG. 3(i) andFIG. 3(j). It can, therefore, be seen that the summing amplifer outputsignal is a composite signal thereof, which may, for example, take theshape of the solid line waveform shown in FIG. 3(m), and, therefore,represents a modified version of the submarine vehicle deviation fromthe set point altitude at any given instant. This signal is fed tovoltage level detector 38 to determine if the threshold voltage(represented by the dashed line of FIG. 3(m) has been achieved. If so,an output signal therefrom similar to that depicted in FIG. 3(n) timelyenergizes relay 39, which, in turn, actuates vehicle control surface 41to effect an up-elevator condition. On the other hand, if the aforesaidthreshold voltage has not been achieved, no voltage occurs at the outputof voltage level detector 38, relay 39 remains deenergized, and vehiclecontrol surface 41 is automatically urged to a down-elevator position.Of course, as is conventional in such vehicles, a change in position ofthe control surface changes the attitude thereof to move it up or downrelative to the sea floor, as it moves along its intended course.

Maximum dive angle regulator 43 is preferably incorporated in thisinvention, is physically connected to vehicle 42, and is electricallyconnected to relay 39. In event a vehicle nose-down pitch greater than,for example, thirty degrees from the horizontal inadvertently occurs,maximum dive angle regulator 43 supplies a voltage which overrides thedownelevator no voltage signal by voltage level detector 38 and callsfor an up-elevator signal by energizing relay 39. In such case, theoutput voltage waveform from voltage level detector 38 is modulated bysaid maximum dive angle regulator overriding voltage to effect awaveform comparable to that exemplarily illustrated in FIG. 3(0), withthe square wave portion thereof representing said overriding voltagemodulation. Hence, relay 39 would be energized in accordance with thevoltage waveform disclosed in FIG. 3(p).

As previously suggested, a conventional switch and conventionalassociated circuitry may be used as maximum dive angle regulator 43 inthe same manner as they are used in the typical level control arts.

Accordingly, it may readily be seen that either an up vehicle controlsurface position of a down vehicle control surface position is calledfor at all times by this invention; and that an up position is calledfor if the vehicle being controlled has deviated from the set altitudeposition and is too near the ocean bottom, and a down position is calledfor if the vehicle has deviated from the set altitude position and istoo far from the ocean bottom.

It may, therefore, be seen from the simplified quasi-pictorial view ofFIG. 4 that a movable submarine vehicle, whether selfpropelled or towed,will echo-range on the sea floor from any given subaqueous altitude,seek a predetermined set altitude above said sea floor, and hunttherealong, as it travels on its course.

Other modifications and embodiments of the subject invention willreadily come to the mind of one skilled in the art having the benefit ofthe teachings presented in the foregoing description and the drawings.It is, therefore, to be understood that this invention is not to belimited thereto and that said modifications and embodiments are intendedto be included within the scope of the appended claims.

What is claimed is: 1. A system for controlling the disposition of amovable vehicle at a predetermined distance from a reference datumcomprising in combination:

means for broadcasting a given energy signal toward said reference datumand generating simultaneously therewith a first timing signal;

means for receiving an echo of said given energy signal after it hasbeen reflected from said reference datum and simultaneously generatingtherewith a second timing signal;

means connected to the outputs of said broadcasting and receiving meansfor blanking said second timing signal for a predetermined period oftime in response to said first timing signal;

means effectively connected to the outputs of said broadcasting means,said receiving means, and said blanking means for producinga thirdsignal having a voltage level proportional to the time period occurringbetween said first timing signal and said second timing signal after ithas been blanked said predetermined period of time;

means for generating a fourth signal having a polarized voltageproportional to the aforesaid predetermined distance said movablevehicle is to be controlled from said reference datum;

means connected to the outputs of said third signal producing means andsaid fourth signal generating means for algebraically summing theaforesaid third and fourth signals emanating therefrom;

means attached to the aforesaid movable vehicle for controlling theattitude thereof as it moves along a course; and

means connected between the output of said summing means and the inputof the aforesaid movable vehicle attitude controlling means for guidingsaid movable vehicle in an upwardly direction whenever the sum of saidthird and fourth signals exceeds a predetermined value and for guidingit in a downwardly direction whenever the sum of said third and fourthsignals is less than said predetermined value.

2. The device of claim 1 wherein said means for broadcasting a givenenergy signal toward said reference datum and generating simultaneouslytherewith a first timing signal comprises:

a repetition rate oscillator;

a transmitter means connected to the output of said repetition rateoscillator; and

a transducer connected to the output of said transmitter means.

3. The device of claim 1 wherein said means for receiving an echo ofsaid given energy signal after it has been reflected from said referencedatum and simultaneously generating therewith a second timing signalcomprises:

a transducer;

a receiver connected to the output of said transducer; and

a detector connected to the output of said receiver.

4. The device of claim 1 wherein said means effectively connected to theoutputs of said broadcasting means, said receiving means, and saidblanking means for producing a third signal having a voltage levelproportional to the time period occurring between said first timingsignal and said second timing signal after it has been blanked saidpredetermined period of time comprises:

and AND gate having a pair of inputs and an output, with one of theinputs thereof connected to the output of said blanking means, and withthe other input thereof connected to the output of said receiving means;

a time comparator multivibrator having a pair of inputs and an output,with one of the inputs thereof effectively connected to the output ofsaid broadcasting means for response to said first timing signal, andwith the other input thereof connected to the output of said receivingmeans for response to said second timing signal; and

an integrator connected to the output of the aforesaid time comparatormultivibrator.

5. A system for guiding a submarine vehicle in such manner that it willhunt along a predetermined altitude above the sea floor comprising incombination:

a submarine vehicle adapted for being propelled through sea water;

movable elevator means mounted on said submarine vehicle for controllingthe up and down travel direction thereof, as it is propelled throughsaid sea water;

means effectively mounted on said submarine vehicle for broadcasting anacoustical signal toward said sea floor;

generator means, having an input connected to said acoustical signalbroadcasting means and a pair of outputs, for producing a first timingsignal and a blanking signal of predetermined duration at the instantsaid acoustical signal is broadcast;

means effectively mounted on said submarine vehicle for receiving anecho of said broadcast acoustical signal after it has been reflectedfrom said sea floor and simultaneously generating therewith a secondtiming signal;

an AND gate, having a pair of inputs and an output. with one of theinputs thereof connected to the blanking signal output of said generatormeans and with the other input thereof connected to the second timingsignal output of the aforesaid receiving means;

a time comparator multivibrator. having a pair of inputs and an outputwith one of the inputs thereof connected to the output of said AND gate,and with the other input thereof connected to the first timing signaloutput of said generator means, for producing a square wave outputsignal having a duration equal to the time period occurring between theaforesaid first and second timing signals after said second timingsignal has been blanked for the duration of said blanking signal;

an integrator connected to the output of said time comparatormultivibrator;

a vehicle pitch analog voltage generator;

an altitude set voltage generator;

a summing amplifier having a trio of inputs and an output, with one ofthe inputs thereof connected to the output of said integrator withanother of the inputs thereof connected to the output of said vehiclepitch analog voltage generator. and the remaining input thereofconnected to the output of said altitude set voltage generator;

a voltage level detector connected to the output of said summingamplifier;

a relay having a pair of inputs and an output, with one of the inputsthereof connected to the output of said voltage level detector, and withthe output thereof connected to the aforesaid elevator means for up anddown movement thereof; and

maximum dive angle regulator connected to the other input of said relayfor actuation thereof in such manner as to effect an up elevatorcondition, whenever the dive angle of said submarine vehicle exceeds apredetermined angle with respect to the horizontal.

6. The invention according to claim 5 further characterized by a readoutmeans connected to said integrator for continuously indicating andrecording the output thereof in terms of submarine vehicle altitudeabove the sea floor.

7. The device of claims 5 wherein said means effectively mounted on saidsubmarine vehicle for broadcasting an acoustical signal toward said seafloor is:

a sonar transmitter; and

an electroacoustical transmitting transducer connected to the output ofsaid sonar transmitter.

8. The device of claim 5 wherein said means effectively mounted on saidsubmarine vehicle for receiving an echo of said broadcast acousticalsignal after it has been reflected from said sea floor andsimultaneously generating there with a second timing signal comprises:

an electroacoustical receiving transducer; and

a sonar receiver connected to the output of said electroacousticalreceiving transducer.

9. The invention according to claim 8 further characterized by adetector connected to the output of said sonar receiver.

1|: t: I: t l

1. A system for controlling the disposition of a movable vehicle at apredetermined distance from a reference datum comprising in combination:means for broadcasting a given energy signal toward said reference datumand generating simultaneously therewith a first timing signal; means forreceiving an echo of said given energy signal after it has beenreflected from said reference datum and simultaneously generatingtherewith a second timing signal; means connected to the outputs of saidbroadcasting and receiving means for blanking said second timing signalfor a predetermined period of time in response to said first timingsignal; means effectively connected to the outputs of said broadcastingmeans, said receiving means, and said blanking means for producing athird signal having a voltage level proportional to the time periodoccurring between said first timing signal and said second timing signalafter it has been blanked said predetermined period of time; means forgenerating a fourth signal having a polarized voltage proportional tothe aforesaid predetermined distance said movable vehicle is to becontrolled from said reference datum; means connected to the outputs ofsaid third signal producing means and said fourth signal generatingmeans for algebraically summing the aforesaid third and fourth signalsemanating therefrom; means attached to the aforesaid movable vehicle forcontrolling the attitude thereof as it moves along a course; and meansconnected between the output of said summing means and the input of theaforesaid movable vehicle attitude controlling means for guiding saidmovable vehicle in an upwardly direction whenever the sum of said thirdand fourth signals exceeds a predetermined value and for guiding it in adownwardly direction whenever the sum of said third and fourth signalsis less than said predetermined value.
 2. The device of claim 1 whereinsaid means for broadcasting a given energy signal toward said referencedatum and generating simultaneously therewith a first timing signalcomprises: a repetition rate oscillator; a transmitter means connectedto the output of said repetition rate oscillator; and a transducerconnected to the output of said transmitter means.
 3. The device ofclaim 1 wherein said means for receiving an echo of said given energysignal after it has been reflected from said reference datum andsimultaneously generating therewith a second timing signal comprises: atransducer; a receiver connected to the output of said transducer; and adetector connected to the output of said receiver.
 4. The device ofclaim 1 wherein said means effectively connected to the outputs of saidbroadcasting means, said receiving means, and said blanking means forproducing a third signal having a voltage level proportional to the timeperiod occurring between said first timing signal and said second timingsignal after it has been blanked said predetermined period of timecomprises: and AND gate having a pair of inputs and an output, with oneof the inputs thereof connected to the output of said blanking means,and with the other input thereof connected to the output of saidreceiving means; a time comparator multivibrator having a pair of inputsand an output, with one of the inputs thereof effectively connected tothe output of said broadcasting means for response to said first timingsignal, and with the other input thereof connected to the output of saidreceiving means for response to said second timing signal; and anintegrator connected to the output of the aforesaid time comparatormultivibrator.
 5. A system for guiding a submarine vehicle in suchmanner that it will hunt along a predetermined altitude above the seafloor comprising in combination: a submarine vehicle adapted for beingpropelled through sea water; movable elevator means mounted on saidsubmarine vehicle for controlling the up and down travel directionthereof, as it is propelled through said sea water; means effectivelymounted on said submarine vehicle for broadcasting an acoustical signaltoward said sea floor; generator means, having an input connected tosaid acoustical signal broadcasting means and a pair of outputs, forproducing a first timing signal and a blanking signal of predeterminedduration at the instant said acoustical signal is broadcast; meanseffectively mounted on said submarine vehicle for receiving an echo ofsaid broadcast acoustical signal after it has been reflected from saidsea floor and simultaneously generating therewith a second timingsignal; an AND gate, having a pair of inputs and an output, with one ofthe inputs thereof connected to the blanking signal output of saidgenerator means, and with the other input thereof connected to thesecond timing signal output of the aforesaid receiving means; a timecomparator multivibrator, having a pair of inputs and an output, withone of the inputs thereof connected to the output of said AND gate, andwith the other input thereof connected to the first timing signal outputof said generator means, for producing a square wave output signalhaving a duration equal to the time period occurring between theaforesaid first and second timing signals after said second timingsignal has been blanked for the duration of said blanking signal; anintegrator connected to the output of said time comparatormultivibrator; a vehicle pitch analog voltage generator; an altitude setvoltage generator; a summing amplifier having a trio of inputs and anoutput, with one of the inputs thereof connected to the output of saidintegrator, with another of the inputs thereof connected to the outputof said vehicle pitch analog voltage generator, and the remaining inputthereof connected to the output of said altitude set voltage generator;a voltage level detector connected to the output of said summingamplifier; a relay having a pair of inputs and an output, with one ofthe inputs thereof connected to the output of said voltage leveldetector, and with the output thereof connected to the aforesaidelevator means for up and down movement thereof; and a maximum diveangle regulator connected to the other input of said relay for actuationthereof in such manner as to effect an up elevator condition, wheneverthe dive angle of said submarine vehicle exceeds a predetermined anglewith respect to the horizontal.
 6. The invention according to claim 5further chAracterized by a readout means connected to said integratorfor continuously indicating and recording the output thereof in terms ofsubmarine vehicle altitude above the sea floor.
 7. The device of claims5 wherein said means effectively mounted on said submarine vehicle forbroadcasting an acoustical signal toward said sea floor is: a sonartransmitter; and an electroacoustical transmitting transducer connectedto the output of said sonar transmitter.
 8. The device of claim 5wherein said means effectively mounted on said submarine vehicle forreceiving an echo of said broadcast acoustical signal after it has beenreflected from said sea floor and simultaneously generating there with asecond timing signal comprises: an electroacoustical receivingtransducer; and a sonar receiver connected to the output of saidelectroacoustical receiving transducer.
 9. The invention according toclaim 8 further characterized by a detector connected to the output ofsaid sonar receiver.